Heatable luminaire cover

ABSTRACT

A heatable luminaire cover is described. The heatable luminaire cover has a polymeric main body, a first busbar, a second busbar and at least two conductor tracks on the inside of the polymeric main body.

The invention relates to a heatable luminaire cover, a method for itsproduction, and its use.

The effectiveness of motor vehicle lighting can be impaired at lowambient temperatures, in particular in the winter. Snow, ice, or orcondensed atmospheric moisture can accumulate on the outer side of thecover of the motor vehicle luminaire. Atmospheric moisture can alsocondense and freeze on the inner side of the luminaire cover. Thislessens the transparency of the luminaire cover and reduces thefunctionality of the lighting. Road safety is disadvantageouslyaffected.

Motor vehicle headlights were formerly equipped primarily with halogenlamps or xenon lamps. These lamps develop significant heat duringoperation. The heat is transferred to the luminaire cover and results indefrosting and/or drying of the luminaire cover. Nowadays, motor vehicleheadlights are increasingly equipped with light emitting diodes (LED),which generate significantly less heat during operation. Consequently,active heating of the luminaire cover is necessary for the removal ofmoisture and ice.

US 2006/0232972 A1 discloses a method for producing a cover for a motorvehicle lamp. A heating wire and two electrical connection elements areapplied on a flat plastic plate. Each end of the heating wire is weldedto an electrical connection element. Then, the luminaire cover made ofthe plastic plate is shaped by thermoforming. There is a risk ofdamaging the heating wire or making a connection between the heatingwire and an electrical connection element. Moreover, the thermoformingmethod restricts the design freedom with regard to the shape of theluminaire cover. The electrical contacting is also error prone: If theelectrically conductive connection between the two connection elementsis interrupted, for example, by a break in the heating wire, the heatingfunction fails completely.

One object of the present invention is to provide a heatable luminairecover with improved electrical contacting of the heating structures.Another object of the invention is to provide a method for producing aheatable luminaire cover wherein damaging of the heating structures isavoided.

The object of the present invention is accomplished according to theinvention by a heatable luminaire cover in accordance with theindependent claim 1. Preferred embodiments emerge from the dependentclaims.

The heatable luminaire cover according to the invention comprises atleast the following characteristics:

-   -   a polymeric main body,    -   a first busbar, a second busbar, and at least two conductor        tracks on the inner side of the polymeric main body, wherein        each conductor track is electrically connected to the first        busbar and to the second busbar.

The term “inner side” refers to the surface of the polymeric main bodythat is intended to be turned toward the light source after theconnection of the heatable luminaire cover to the other elements of thelamp. The term “outer side” is, accordingly, the surface of thepolymeric main body that is intended to be turned away from the lightsource after the connection of the heatable luminaire cover to the otherelements of the lamp.

Upon application of an electrical potential difference between the firstand second busbar, current flows through each of the conductor tracks.By this means, the conductor tracks, which thus enable active heating ofthe luminaire cover, are heated.

By means of the first and the second busbar, a stable electricalcontacting of the conductor tracks is advantageously provided. Eachconductor track is electrically connected to the first and the secondbusbar and is supplied with voltage independently of the other conductortracks. The damaging of one conductor track thus does not result in acomplete failure of the active heating of the luminaire cover. This is amajor advantage of the present invention.

The object of the present invention is further accomplished according tothe invention by a method for producing a heatable luminaire cover,wherein at least:

-   -   a) one polymeric main body is provided,    -   b) at least two conductor tracks are fixed on the inner side of        the polymeric main body by ultrasonic embedding, and    -   c) each conductor track is electrically connected to a first        busbar and a second busbar.

The polymeric main body has the typically curved three-dimensional shapeprovided for the luminaire cover. The polymeric main body does not haveto be further reshaped before connection to the remaining elements ofthe lamp. Processing steps that are not associated with changing thecurvature of the polymeric main body, for example, drilling, milling, orcutting in the edge region, are, however, possible within the context ofthe invention.

The polymeric main body of the luminaire cover is provided according tothe invention before the conductor tracks are applied. Consequently, theconductor tracks are not stressed during the shaping of the polymericmain body. The particular advantage resides in the avoidance of damageto the conductor tracks and/or to the electrical contacting of theconductor tracks. Moreover, by means of the first and the second busbar,a stable electrical contacting of each individual conductor track isprovided.

The polymeric main body can be produced by all suitable methods ofplastic processing known to the person skilled in the art, for example,by thermoforming. In a preferred embodiment of the invention, thepolymeric main body is produced by injection molding. Compared tothermoforming, injection molding enables the production of a largernumber of possible shapes of the polymeric main body. Moreover, thepolymeric main body can be produced virtually waste free sincesubsequent trimming of the workpiece is unnecessary. Complex surfacestructures can be introduced directly into the cover.

The polymeric main body preferably contains at least polyethylene (PE),polycarbonates (PC), polypropylene (PP), polystyrene, polybutadiene,polynitriles, polyesters, polyurethanes, polymethyl methacrylates,polyacrylates, polyesters, polyamides, polyethylene terephthalate,acrylonitrile butadiene styrene (ABS), styrene acrylonitrile (SAN),acrylonitrile styrene acrylester (ASA), acrylonitrile butadienestyrene-polycarbonate (ABS/PC), and/or copolymers or mixtures thereof.

The polymeric main body particularly preferably contains polycarbonates(PC) and/or polymethyl methacrylate (PMMA). This is particularlyadvantageous with regard to the transparency, the processing, thestrength, the weather resistance, and the chemical resistance of thepolymeric main body.

The polymeric main body preferably has a thickness from 2 mm to 5 mm.This is particularly advantageous with regard to the strength andprocessing of the polymeric main body. The size of the polymeric mainbody can vary widely and is determined by the use according to theinvention.

According to the invention, the polymeric main body is transparent atleast in regions. The polymeric main body can be colorless, colored, ortinted. The polymeric main body can be clear or cloudy.

The conductor tracks preferably run rectilinearly between the first andthe second busbar. The conductor tracks can, however, also run, forexample, wavelike, meanderingly, or in the form of a zigzag patternbetween the first and second busbar. The distance between two adjacentconductor tracks is preferably constant over the entire length of theconductor tracks. However, the distance between two adjacent conductortracks can also change in the path between the first and second busbar.

The conductor tracks can run in any desired direction, preferablyhorizontally or vertically.

The conductor tracks are applied according to the invention on thepolymeric main body by means of ultrasonic embedding. A sonotrode ispreferably guided over the inner side of the polymeric main body by amulti-axis robot by means of a robot program adapted to thethree-dimensional geometry of the polymeric main body. The sonotrodetransmits high-frequency mechanical oscillations (ultrasound) generatedby an ultrasonic generator to the polymeric main body. Heat is generatedand a surface layer of the inner side of the polymeric main body ismelted. The conductor tracks are introduced into the melted surfacelayer. For this, the sonotrode guides a heating wire on its tip, withthe heating wire continuously supplied from a spool of wire near thesonotrode. A tool suitable as a sonotrode is known, for example, fromU.S. Pat. No. 6,023,837 A.

The penetration depth of the conductor tracks into the polymeric mainbody is preferably from 50% to 90%, particularly preferably from 60% to75% of the thickness of the conductor tracks. The uncomplicatedapplication of the conductor tracks using ultrasound embedding isparticularly advantageous with regard to a stable connection betweenconductor tracks and a polymeric main body.

The distance between two adjacent conductor tracks is preferably from 1mm to 25 mm, particularly preferably 3 mm to 15 mm. This is particularlyadvantageous with regard to the transparency of the luminaire cover andthe distribution of the heating power introduced via the conductortracks. The length of the conductor tracks can vary widely and thus bereadily adapted to the requirements in the individual case. Theconductor tracks have, for example, lengths from 5 cm to 50 cm.

The conductor tracks contain at least one metal, preferably tungsten,copper, nickel, manganese, aluminum, silver, chromium, and/or iron, aswell as mixtures and/or alloys thereof. The conductor tracks containparticularly preferably tungsten and/or copper. A particularly goodheating effect is thus achieved. The thickness of the conductor tracksis preferably from 15 μm to 200 μm, particularly preferably from 25 μmto 90 μm. This is particularly advantageous with regard to thetransparency of the luminaire cover, the heating power introduced, andthe avoidance of short circuits.

It has been demonstrated that particularly good results are obtainedwith conductor tracks that contain tungsten and have a thickness ofpreferably 15 μm to 100 μm, particularly preferably from 25 μm to 50 μm.Particularly good results are also achieved with conductor tracks thatcontain copper and have a thickness of preferably 25 μm to 200 μm,particularly preferably 60 μm to 90 μm.

Adjacent conductor tracks can be connected to each other on the side ofthe first busbar facing away from the second busbar or on the side ofthe second busbar facing away from the first busbar. The conductortracks can thus be applied in the form of a single heating wire on thepolymeric main body, with the heating wire, after application,comprising two or more sections that are provided as conductor tracksand are connected to each other loop-wise. Each section of the heatingwire provided as a conductor track is connected in the region of one endto the first busbar and in the region of the other end to the secondbusbar. Each section of the heating wire in the region of the busbarsand between the busbars forms a conductor track.

Alternatively, it is possible for adjacent conductor tracks to not beconnected to each other on the side of the first busbar facing away fromthe second busbar and on the side of the second busbar facing away fromthe first busbar. The conductor tracks are thus applied on the polymericmain body in the form of a plurality of heating wires, with each heatingwire connected in the region of one end to the first busbar and in theregion of the other end to the second busbar. Each heating wirecomprises a conductor track in the region of the busbars and between thebusbars.

At least one section of each conductor track is embedded into thepolymeric main body. The conductor tracks can be embedded into thepolymeric main body along their entire length. This is particularlyadvantageous with regard to a stable connection between the polymericmain body and the conductor tracks. The electrical contacting with thefirst and the second busbar then takes place on the side of theconductor tracks facing away from the polymeric main body.

In an advantageous embodiment of the invention, the regions on the endsof the conductor tracks provided for electrical contacting with thebusbars are not embedded into the polymeric main body and can be liftedoff it. The particular advantage resides in the possibility of a simpleand stable electrical contacting with the busbars. The busbars arepreferably arranged on the polymeric main body and fixed thereon, forexample, with an adhesive or a double-sided adhesive tape. The region onthe end of each conductor track not embedded into the polymeric mainbody is guided over the first busbar on the side of the first busbarfacing away from the polymeric main body and connected to the firstbusbar. The region on the other end of each conductor track not embeddedinto the polymeric main body is guided over the second busbar on theside of the second busbar facing away from the polymeric main body andconnected to the second busbar.

In a particularly preferred embodiment, a first lower busbar and asecond lower busbar are arranged on the polymeric main body. The regionon the end of each conductor track not embedded into the polymeric mainbody is arranged between the first lower busbar and a first upper busbarand is connected to the first lower and the first upper busbar. Theregion on the other end of each conductor track not embedded into thepolymeric main body is arranged between the second lower busbar and asecond upper busbar and is connected to the second lower and the secondupper busbar. The particular advantage resides in an effective and verystable electrical contacting of the conductor tracks. For the heating ofthe luminaire cover, a first electrical potential is applied to thefirst lower busbar and the first upper busbar. A second electricalpotential is applied to the second lower busbar and the second upperbusbar.

The electrical connection between the conductor tracks and the busbarsis preferably done by means of an electrically conductive adhesive, bysoldering, or by welding.

The busbars preferably contain tungsten, copper, nickel, manganese,aluminum, silver, chromium, and/or iron, as well as mixtures and/oralloys thereof, particularly preferably tungsten and/or copper. Thebusbars preferably have a thickness from 10 μm to 200 μm, particularlypreferably from 50 μm to 100 μm. The width of a busbar, along which thebusbar is connected to the conductor tracks, is preferably from 2 mm to100 mm, particularly preferably from 5 mm to 20 mm. The length of thebusbars can vary widely and and thus be ideally adapted to therequirements of the individual case. The minimum length of the busbarsresults from the number of conductor tracks and the distance between theadjacent conductor tracks. The length of the busbars is, for example,from 5 cm to 20 cm. The busbars are connected to an external powersupply such that an electric potential difference between the first andthe second busbar can be applied.

For aesthetic reasons, it can be desirable for the electrical contactingof the conductor tracks by means of the busbars to not be visible fromthe outside. To that end, for example, the polymeric main body can becolored or blackened in the region of the busbars. The polymeric mainbody can, for example, be produced by multicomponent injection molding,with the polymeric main body comprising, in the regions on which thebusbars are to be arranged, an opaque component which obscures the viewof the electrical contacting through the polymeric main body.

The opaque component of the polymeric main body preferably contains atleast polyethylene (PE), polycarbonates (PC), polypropylene (PP),polystyrene, polybutadiene, polynitriles, polyesters, polyurethanes,polymethyl methacrylates, polyacrylates, polyesters, polyamides,polyethylene terephthalate, acrylonitrile butadiene styrene (ABS),styrene acrylonitrile (SAN), acrylonitrile styrene acrylester (ASA),acrylonitrile butadiene styrene-polycarbonate (ABS/PC), and/orcopolymers or mixtures thereof, particularly preferably polycarbonates(PC), polyethylene terephthalate (PET), and/or polymethyl methacrylate(PMMA).

The opaque component of the polymeric main body preferably contains atleast one colorant. The opacity of the component is achieved by means ofthe colorant. The colorant can contain inorganic and/or organic dyesand/or pigments. The colorant can be colored or uncolored. Suitablecolorants are known to the person skilled in the art and can, forexample, be looked up in the Colour Index of the British Society ofDyers and Colourists and the American Association of Textile Chemistsand Colorists. Preferably, a black pigment is used as the colorant, forexample, carbon black, aniline black, bone black, iron oxide black,spinel black, and/or graphite. Thus, a black opaque component isobtained.

The opaque component may contain other inorganic or organic fillers,particularly preferably SiO₂, Al₂O₃, TiO₂, clay minerals, silicates,zeolites, glass fibers, carbon fibers, glass beads, organic fibers,and/or mixtures thereof. The fillers can further increase the stabilityof the opaque component. Moreover, the fillers can lessen the amount ofpolymeric materials and thus reduce the production costs of thecomponent.

Alternatively, a colored or blackened element can be arranged betweenthe busbar and the polymeric main body. Alternatively, masking screenprints can be applied on a surface of the polymeric main body.

In an advantageous embodiment of the invention, a protective coating isapplied on the outer side of the polymeric main body to protect theluminaire cover according to the invention against environmentalinfluences. Preferably used are thermally hardening or UV-hardeningcoating systems based on polysiloxanes, polyacrylates,polymethacrylates, and/or polyurethanes. The protective coatingpreferably has a layer thickness from 1 μm to 50 μm, particularlypreferably from 2 μm to 25 μm. The particular advantage resides in theincreased scratch resistance and weather resistance of the polymericmain body due to the protective coating.

In addition to coloring compounds and pigments, the protective coatingcan also contain UV-blockers and preservatives as well as components toincrease scratch resistance, for example, nanoparticles.

The protective coating can, for example, be applied to the outer side ofthe polymeric main body by a dipping, flooding, or spraying method.After application, the protective coating is hardened preferably bytemperature and/or UV light input. In the case of production of thepolymeric main body by injection molding, the protective coating canalso be applied to the outer side of the polymeric main body by anin-mold coating method.

Products suitable as a protective coating are, for example, AS4000,AS4700, PHC587, or UVHC300, provided by the company Momentive.

The protective coating can also comprise a plurality of layers,preferably an adhesion-promoting layer on the polymeric main body and alacquer coating on the adhesion-promoting layer. The adhesion-promotinglayer can contain, for example, acrylates and have a layer thicknessfrom 0.4 μm to 5 μm. The lacquer coating can contain, for example,polysiloxanes and have a layer thickness from 1 pm to 15 pm. Theadhesion-promoting layer is preferably dried after application, beforethe lacquer coating is applied.

The protective coating can be applied before or after the application ofthe conductor tracks and busbars. The protective coating can be appliedbefore or after the connection of the conductor tracks to the busbars.

The heatable luminaire cover is preferably used as a cover for lights ofmeans of transportation for travel on land, in the air, or on water, inparticular for headlights, taillights, side-marker lights, and/orposition lights of passenger cars, trucks, buses, streetcars, subways,trains, and motorcycles.

The invention is explained in detail with reference to drawings andexemplary embodiments. The drawings are schematic representations andnot true to scale. The drawings in no way restrict the invention. Theydepict:

FIG. 1 a plan view of the inner side of a first embodiment of theheatable luminaire cover according to the invention,

FIG. 2 a plan view of the inner side of another embodiment of theheatable luminaire cover according to the invention,

FIG. 3 a section along A-A′ through the heatable luminaire cover of FIG.1,

FIG. 4 a section along B-B′ through the heatable luminaire cover of FIG.1,

FIG. 5 a section along B-B′ through another embodiment of the heatableluminaire cover according to the invention,

FIG. 6 a section along B-B′ through another embodiment of the heatableluminaire cover according to the invention, and

FIG. 7 a detailed flowchart of the method according to the invention forproducing a heatable luminaire cover.

FIG. 1, FIG. 3, and FIG. 4 each depict a detail of a luminaire cover 10according to the invention for a passenger car headlight. The polymericmain body 1 contains polycarbonate (PC) and has a thickness of 4 mm. Sixheating wires with a length of 20 cm are arranged as conductor tracks 2on the inner side (I) of the polymeric main body. The conductor tracks 2are arranged horizontally and parallel to each other. The conductortracks 2 contain copper and have a thickness of 70 μm. The distancebetween two adjacent heating wires is 10 mm. The conductor tracks 2 areembedded into the polymeric main body over their entire length by meansof ultrasonic embedding, with the penetration depth being roughly 45 μm.

Each conductor track 2 is electrically connected to two busbars 3. Theelectrical connection between the conductor tracks 2 and the busbars 3is made via an electrically conductive adhesive 5. The busbars 3 containcopper and have a thickness of 50 μm, a length of 6 cm, and a width of 1cm.

The busbars 3 are connected to an external power supply (not shown).Upon application of a potential difference between the first busbar 3and the second busbar 3, current flows through each conductor track 2.The heat generated enables active heating of the luminaire cover 10. Dueto the electrical contacting of the individual conductor tracks 2independently of each other according to the invention, the damaging ofone conductor track 2 advantageously does not result in a completefailure of the heating in the luminaire cover 10.

FIG. 2 depicts a plan view of an alternative embodiment of the luminairecover 10 according to the invention. Eleven conductor tracks 2 arearranged on the inner side (I) of the polymeric main body 1. Theconductor tracks 2 are arranged vertically and parallel to each other.The conductor tracks 2 are sections of a single heating wire that isapplied on the polymeric main body 1 in straight sections connected toeach other loop-wise. Adjacent conductor tracks 2 are thus connected toeach other by a region of the heating wire, with the connectionoccurring alternatingly on the side of the second busbar 3 facing awayfrom the first busbar 3 and on the side of the first busbar 3 facingaway from the second busbar 3.

FIG. 3 depicts a section along A-A′ through the heatable luminaire cover10 according to the invention of FIG. 1. The polymeric main body 1 andconductor tracks 2 embedded therein, running horizontally and inparallel, as well as the busbar 3 situated behind the section line A-A′and the electrically conductive adhesive 5 can be seen.

FIG. 4 depicts a section along B-B′ through the heatable luminaire cover10 according to the invention of FIG. 1. Busbars 3, which run verticallyand are glued with an electrically conductive adhesive 5 onto thepolymeric main body 1 and the conductor tracks 2, are depicted.

FIG. 5 depicts a section along B-B′ through an alternative embodiment ofthe heatable luminaire cover 10 according to the invention. In the tworegions of the electrical contacting, the conductor tracks 2 are notembedded into the polymeric main body 1. Each conductor track 2 isarranged in a region between a first lower busbar 3 a and a first upperbusbar 3 b not embedded into the polymeric main body 1. Each conductortrack 2 is arranged in the other region between a second lower busbar 3a and a second upper busbar 3 b not embedded into the polymeric mainbody 1. The conductor tracks 2 are connected by means of a solderingcompound 6 to the busbars 3 a, 3 b. The soldering compound 6 containssilver. The first lower busbar 3 a and the second lower busbar 3 a arefixed on the polymeric main body 1 by means of a double-sided adhesivetape 8.

The polymeric main body 1 is produced by multicomponent injectionmolding. The polymeric main body 1 contains a transparent component 11with a thickness of 4 mm. An opaque component 12 with a thickness of 2mm is applied in regions of the transparent component 11. Thetransparent component 11 contains polycarbonate (PC). The opaquecomponent 12 contains a mineral-filled polycarbonate (PC)-polyethyleneterephthalate (PET) mixture. The starting material for the injectionmolding of the opaque component 12 was prepared by the company TeijinChemicals Ltd. (Panlite Y-0346 Color No. TG6654). The busbars 3 a arearranged on the opaque component 12. Thus, the view of the electricalcontacting of the conductor tracks 2 by means of the busbars through thepolymeric main body 1 is advantageously obscured.

A protective coating 7 is applied on the outer side (II) of thepolymeric main body 1. The protective coating 7 contains a thermallyhardening polysiloxane-based lacquer (Momentive PHC587) and has a layerthickness of 15 μm. By means of the protective coating 7, the polymericmain body 1 is advantageously protected against environmental influencessuch as weathering and mechanical action.

FIG. 6 depicts a section along B-B′ through an alternative embodiment ofthe heatable luminaire cover 10 according to the invention. In theregion of the electrical contacting of the conductor tracks 2, theopaque component 12 extends from the inner side (I) of the polymericmain body 1 to the outer side (II) of the polymeric main body 1. Theview of the electrical contacting of the conductor tracks 2 by means ofthe busbars through the polymeric main body 1 is advantageouslyobscured.

FIG. 7 depicts a flowchart of an exemplary embodiment of the methodaccording to the invention for producing a heatable luminaire cover(10). In a first step, a polymerer main body 1 is produced in theinjection molding process. The polymeric main body 1 containspolycarbonate. The polymeric main body 1 has a thickness of 4 mm and thethree-dimensional, curved shape provided for the luminaire cover (10).Then, heating wires are applied by ultrasonic embedding as conductortracks 2 on the inner side (I) of the polymeric main body 1. Theconductor tracks 2 contain copper and have a thickness of 70 μm. Theconductor tracks 2 are embedded along their entire length into thepolymeric main body 1, with the penetration depth of the conductortracks 2 into the polymeric main body 1 being roughly 45 μm. Then, afirst busbar 3 and a second busbar 3 are connected to each conductortrack 2 via an electrically conductive adhesive 5.

In an alternative preferred embodiment, the regions on the ends of theconductor tracks 2 provided for the electrical contacting with thebusbars 3 are not embedded into the polymeric main body 1. After theapplication of the conductor tracks 2, a first lower busbar 3 a and asecond lower busbar 3 a are arranged with a double-sided adhesive tape 8on the polymeric main body 1. The region on one end of each conductortrack 2 not embedded into the polymeric main body 1 is guided over thefirst lower busbar 3 a. The region on the other end of each conductortrack 2 not embedded into the polymeric main body 1 is guided over thesecond lower busbar 3 a. Soldering compound 6 is arranged on the firstlower busbar 3 a and the second lower busbar 3 a. Then, a first upperbusbar 3 b is arranged above the first lower busbar 3 a and a secondupper busbar 3 b is arranged above the second lower busbar 3 a. Thefirst lower busbar 3 a and the first upper busbar 3 b as well as thesecond lower busbar 3 a and the second upper busbar 3 b are soldered tothe conductor tracks 2 by the input of energy.

In the method according to the invention, the polymeric main body 1 isprepared before the conductor tracks 2 are applied. Thus, in contrast tothe prior art, the conductor tracks 2 are not stressed by reshapingsteps after the application of the conductor tracks 2. Damaging of theconductor tracks 2, of the busbars 3, or of the connection between aconductor track 2 and a busbar 3 was detected in none of the testspecimens prepared.

The conductor tracks 2 according to the invention enabled the removal ofcondensed atmospheric moisture and ice from the luminaire cover (10)within a short time. Due to the the electrical contacting of eachconductor track 2 by means of the busbars 3 deviating from the priorart, even intentionally caused damage of a single conductor track 2 didnot result in the complete failure of the heating action.

This result was was unexpected and surprising for the person skilled inthe art.

LIST OF REFERENCE CHARACTERS

(1) polymeric main body

(2) conductor track

(3) busbar

(3 a) lower busbar

(3 b) upper busbar

(5) electrically conductive adhesive

(6) soldering compound

(7) protective coating

(8) double-sided adhesive tape

(10) heatable luminaire cover

(11) transparent component of 1

(12) opaque component of 1

(I) inner side of the polymeric main body 1

(II) outer side of the polymeric main body 1

A-A′ section line

B-B′ section line

1. A heatable luminaire cover, comprising at least: a polymeric mainbody, a first busbar, a second busbar, and at least two conductor trackson an inner side of the polymeric main body, wherein each conductortrack is electrically connected to the first busbar and to the secondbusbar.
 2. The luminaire cover according to claim 1, wherein at leastone section of each conductor track is embedded into the polymeric mainbody.
 3. The luminaire cover according to claim 2, wherein the conductortracks are embedded into the surface of the polymeric main body at adepth that is from 50% to 90%, preferably from 60% to 75% of theirthickness.
 4. The luminaire cover according to claim 1, wherein thepolymeric main body contains at least polycarbonate and/or polymethylmethacrylate.
 5. The luminaire cover according to claim 1, wherein thethickness of the polymeric main body is from 2 mm to 5 mm.
 6. Theluminaire cover according to claim 1, wherein the conductor trackscontain at least tungsten, copper, nickel, manganese, aluminum, silver,chromium, iron, and/or alloys thereof.
 7. The luminaire cover accordingto claim 1, wherein the conductor tracks have a thickness of 15 μm to200 μm, preferably of 25 μm to 90 μm.
 8. The luminaire cover accordingto claim 1, wherein the first busbar and the second busbar contain atleast tungsten, copper, nickel, manganese, aluminum, silver, chromium,iron, and/or alloys thereof.
 9. The luminaire cover according to claim1, wherein a protective coating that contains at least a polysiloxane, apolyacrylate, a poly methacrylate, and/or a polyurethane and preferablyhas a thickness from 1 μm to 50 μm, particularly preferably from 2 μm to25 μm is arranged on an outer side of the polymeric main body.
 10. Theluminaire cover according to claim 1, wherein the conductor tracks areelectrically connected to the first busbar and the second busbar via asoldering compound.
 11. The luminaire cover according to claim 1,wherein a region of each conductor track is arranged between a firstlower busbar and a first upper busbar and another region of eachconductor track is arranged between a second lower busbar and a secondupper busbar.
 12. A method for producing a heatable luminaire cover,comprising: preparing a polymeric main body, fixing at least twoconductor tracks on an inner side of the polymeric main body byultrasonic embedding, and electrically connecting each conductor trackto a first busbar and a second busbar.
 13. The method according to claim12, wherein a protective coating is applied on an outer side of thepolymeric main body.
 14. The method according to claim 12, wherein thepolymeric main body is prepared by injection molding or bythermoforming.
 15. A method comprising: using the heatable luminairecover according to claim 1, as a cover for lights of means oftransportation for travel on land, in the air, or on water, inparticular for headlights, taillights, side-marker lights, and/orposition lights of passenger cars, trucks, buses, streetcars, subways,trains, and motorcycles.